1. Field of the Invention
The present invention relates to tape systems. More particularly, the present invention relates to tape head systems.
2. Description of the Related Art
In modern tape systems, data is organized in data tracks which are written and read back in a parallel fashion by a read and write head having servo read, data read, and data write elements, i.e. transducer elements. These data tracks run in a longitudinal direction of the magnetic tape and are much narrower than the excursions the magnetic tape experiences in the lateral direction as a result of imperfections in the mechanical entrainment system. Therefore, it is crucial to accurately position the head relative to the magnetic tape as the magnetic tape is streamed. To this end, modern tape systems provide for track-following functionality ensuring that the head follows the lateral motion of the tape as it is transported over the head in order to keep the read and write transducers centered on a desired track location. Also, tape systems are known which provide for a tape skew following functionality ensuring that the head assumes a desired angular orientation with respect to the magnetic tape. The tape skew following functionality is essential in enabling read-while-write-verify functionality as the track width is scaled to smaller dimensions. The track following functionality as well as the skew following functionality can be implemented as closed loop control systems.
One challenge in the design of tape drives is maintaining the performance of the closed loop control systems under vibration conditions. Tape head systems providing the track following or tape skew following functionality are typically implemented with voice coil actuators, and are relatively well-modeled as mass-spring systems with fundamental resonance frequencies in the range of tens of Hz up to 100 Hz. Under typical vibration conditions in tape drives ranging from 0 up to a few hundred Hz, the tape head systems are excited at their fundamental resonance frequency resulting in degraded track following or tape skew following performance. Higher-order resonance modes of the tape head systems are typically well above the frequency range of applied vibrations and are hence not efficiently excited and; therefore, less of an issue.
According to one approach, it is known to add damping to the tape head systems to improve track following and tape skew following performance, especially at the fundamental resonance frequency.